“Necessary” Uses of Recursion in Imperative Languages

Question

I\'ve recently seen in a couple of different places comments along the lines of, \"I learned about recursion in school, but have never used it or felt the need for it since

Answer 1

It's all about the data you are processing.

I wrote a simple parser to convert a string into a data structure, it's probably the only example in 5 years' work in Java, but I think it was the right way to do it.

The string looked like this:

"{ index = 1, ID = ['A', 'B', 'C'], data = {" +
   "count = 112, flags = FLAG_1 | FLAG_2 }}"

The best abstraction for this was a tree, where all leaf nodes are primitive data types, and branches could be arrays or objects. This is the typical recursive problem, a non-recursive solution is possible but much more complex.

Answer 2

It was said "anything tree". I may be too cautious, and I know that stacks are big nowadays, but I still won't use recursion on a typical tree. I would, however, do it on a balanced tree.

Answer 3

In my opinion, recursive algorithms are a natural fit when the data structure is also recursive.

def traverse(node, function):
    function(this)
    for each childnode in children:
        traverse(childnode, function)

I can't see why I'd want to write that iteratively.